Try powerbookmedic.com . Haven't used them before, but I hear they are good.
EDIT:
$50-$70 from PowerBookMedic: http://www.powerbookmedic.com/141-Display-Screen-TFT-Replacement-Complete-Pismo-p-16175.html
UK eBay search: http://www.ebay.co.uk/sch/i.html?_trksid=p5197.m570.l1313&_nkw=PowerBook+G3+LCD&_sacat=0&_from=R40
EDIT:
$50-$70 from PowerBookMedic: http://www.powerbookmedic.com/141-Display-Screen-TFT-Replacement-Complete-Pismo-p-16175.html
UK eBay search: http://www.ebay.co.uk/sch/i.html?_trksid=p5197.m570.l1313&_nkw=PowerBook+G3+LCD&_sacat=0&_from=R40